Programmable shunt with electromechanical valve actuator

ABSTRACT

Devices and methods for regulating and directing bodily fluids from one region of a patient to another region are disclosed. In general, an apparatus is provided that can include an implantable shunt system and a system controller. The implantable shunt system can have an adjustable valve for regulating the flow of fluid, a sensor element for measuring a physiological characteristic of a patient, and an electromechanical valve actuator that can be adapted to adjust a resistance of the valve. The implantable shunt system can be in electrical communication with the system controller. The system controller can generally be adapted to receive a physiological characteristic of the patient and operate the electromechanical valve actuator to adjust a resistance of the valve. The apparatus can also include an external programming device that is in communication with the system controller.

FIELD OF THE INVENTION

The present invention relates to methods and devices for regulating anddirecting bodily fluids from one region of a patient to another region.

BACKGROUND OF THE INVENTION

Hydrocephalus is a neurological condition caused by the abnormalaccumulation of cerebrospinal fluid (CSF) within the ventricles, orcavities, of the brain. Hydrocephalus, which can affect infants,children and adults, arises when the normal drainage of CSF in the brainbecomes blocked in some way. Such blockage can be caused by a number offactors, including, for example, genetic predisposition,intraventricular or intracranial hemorrhage, infections such asmeningitis, or head trauma. Blockage of the flow of CSF consequentlycreates an imbalance between the rate at which CSF is produced by theventricular system and the rate at which CSF is absorbed into thebloodstream. This imbalance increases pressure on the brain and causesthe brain's ventricles to enlarge. Left untreated, hydrocephalus canresult in serious medical conditions, including subdural hematoma,compression of the brain tissue, and impaired blood flow.

Hydrocephalus is most often treated by surgically inserting a shuntsystem to divert the flow of CSF from the ventricle to another area ofthe body, such as the right atrium, the peritoneum, or other locationsin the body where CSF can be absorbed as part of the circulatory system.Various shunt systems have been developed for the treatment ofhydrocephalus. Typically, shunt systems include a ventricular catheter,a shunt valve, and a drainage catheter. At one end of the shunt system,the ventricular catheter can have a first end that is inserted through ahole in the skull of a patient, such that the first end resides withinthe ventricle of a patient, and a second end of the ventricular catheterthat is typically coupled to the inlet portion of the shunt valve. Thefirst end of the ventricular catheter can contain multiple holes orpores to allow CSF to enter the shunt system. At the other end of theshunt system, the drainage catheter has a first end that is attached tothe outlet portion of the shunt valve and a second end that isconfigured to allow CSF to exit the shunt system for reabsorption intothe blood stream.

Generally, the shunt valve, which can have a variety of configurations,is effective to regulate the flow rate of fluid through the shuntsystem. In some shunt valve mechanisms, the fluid flow rate isproportional to the pressure difference at the valve mechanism. Theseshunt valve mechanisms permit fluid flow only after the fluid pressurehas reached a certain threshold level. Thus, when the fluid pressure isslightly greater than the threshold pressure level, the fluid flow rateis relatively low, but as the pressure increases, the fluid flow ratesimultaneously increases. Typically, the shunt valve allows fluid toflow normally until the intracranial pressure has been reduced to alevel that is less than the threshold pressure of the shunt valve,subject to any hysteresis of the device.

Certain conventional shunt valves allow external adjustment of thethreshold pressure level at which fluid flow will commence to avoidinvasive surgical procedures. In some shunt systems, the shunt valvecontains a magnetized rotor to control the pressure threshold of thevalve. Physicians can then use an external adjustment mechanism, such asa magnetic programmer, to adjust the pressure threshold of the shuntvalve. However, these magnetized rotors can be unintentionally adjustedin the presence of a strong external magnetic field, such as during anMRI procedure. Unintentional adjustment of the pressure threshold couldlead to either the overdrainage or underdrainage of CSF, which canresult in dangerous conditions, such as subdural hematoma.

Attempts have been made to provide a locking mechanism that preventsunintentional valve adjustment, even in the presence of a strongexternal magnetic field, while simultaneously allowing intentionaladjustment of the pressure threshold. One such approach has beendetailed in U.S. Pat. No. 5,643,194, in which Negre describes a lockingmeans having two opposed micro-magnets mounted on the rotor. In thepresence of a bi-directional magnetic field, these micro-magnets movelinearly in the rotor, in a substantially radial direction, to activatethe locking means. However, the Negre locking means does not eliminatethe risk of inadvertent valve adjustment in the presence of a strongexternal magnetic field.

Another approach has been described in U.S. Pat. No. 5,637,083, in whichBertrand et al. describe a valve that includes means for locking therotor assembly in a desired position. This locking means uses a pinhaving a first end adapted to engage a series of detents in an outerperipheral surface of the rotor assembly, thereby preventing the rotorassembly from rotating. The locking means is disengaged by apin-actuating means having two levers that move the pin from a first,extended position, i.e., within the detent(s) in the outer peripheralsurface, to a second, retracted position. The first lever is a pivotablelever having a shaft adapted to engage a second end of the pin, whilethe second lever is a manually actuated lever that is biased to urge thepin into the first, extended position. This manually actuated lever,however, is located within the valve chamber that is used to pump, orflush, fluid from the shunt valve. Thus, by virtue of its locationwithin the pumping chamber, the manually actuated lever, andconsequently the pin-actuating means, can impair or inhibit the functionof the pumping chamber.

Accordingly, a need exists for improved methods and devices forregulating cerebrospinal fluid flow.

SUMMARY OF THE INVENTION

Devices and methods for regulating and directing bodily fluids from oneregion of a patient to another region are disclosed. In general, anapparatus is provided that can include an implantable shunt system and asystem controller. While a variety of configurations are available forthe implantable shunt system, in one exemplary embodiment, the systemcan have an adjustable valve for regulating the flow of fluid, a sensorelement for measuring a physiological characteristic of a patient, andan electromechanical valve actuator that can be adapted to adjust aresistance of the valve. The implantable shunt system can be inelectrical communication with the system controller. The systemcontroller can generally be adapted to receive a physiologicalcharacteristic of the patient and operate the electromechanical valveactuator to adjust a resistance of the valve. In one exemplaryembodiment, the sensor element can be a pressure sensor for detecting acerebro-spinal fluid pressure. In another embodiment, the shunt systemcan include a second sensor element for measuring an additionalphysiological characteristic. The apparatus can be battery powered(i.e., by a battery contained therein) or can be powered by an externalcomponent.

In one exemplary embodiment, the valve can take the form of a ball valvethat is operatively associated with an electromechanical valve actuator.While several configurations are available for the electromechanicalvalve actuator, in general, the actuator can include a spring and apressure setting mechanism. A variety of springs can be used with thevalve actuator including, for example, leaf and helical springs. Thepressure setting mechanism can also have a variety of configurations.For example, in one embodiment, the pressure setting mechanism caninclude a motor driven rotor assembly that is adapted to adjust aresistance of the valve upon actuator of the motor. In another exemplaryembodiment, the pressure setting mechanism includes a motor driven stopmember that is adapted to apply a force to the spring to adjust aresistance of the valve.

In general, the system controller can be adapted to receive aphysiological characteristic of the patient and operate theelectromechanical valve actuator to adjust a resistance of the valve. Inone exemplary embodiment, the system controller can include amicroprocessor for comparing measured values to predetermined targetvalues. For example, where the sensor element is a pressure sensor, themicroprocessor can be adapted to compare the measured pressure detectedby the sensor element to a predetermined target pressure. To facilitatethe comparison, the system controller can also be configured to receivean input signal representative of a target value. In addition tocomparing values, the microprocessor can be programmed to calculate adesired resistance for the valve to achieve a target pressure. A varietyof configurations are available for the system controller, including,for example, configurations in which the controller is contained withinthe implantable shunt system and configurations in which the controlleris disposed on an implant separate from the shunt system.

The apparatus for regulating fluid flow can further include an externalprogramming device that is in communication with the system controller.In general, the programming device can include a user input element thatallows an operator to input one or more instructions to be communicatedto the system controller. For example, the external programming devicecan be adapted to transmit a signal to the system controller that isrepresentative of a predetermined target value for the CSF pressure of apatient. The external programming device can have a varietyconfigurations and in one exemplary embodiment can include a displayelement for communicating a physiological characteristic to a user. Inaddition to communicating instructions to the system controller, theprogramming device can also be adapted to power the implantable shuntsystem.

In one exemplary embodiment, the implantable shunt system, systemcontroller, and external programming device can be configured tocommunicate via radiofrequency (RF) communication. In an exemplaryembodiment, the shunt system, system controller, and programming devicecan include signal transmitters/receivers or antennas that can beconfigured to send and/or receive signals from one another. Suchcommunication can provide non-invasive control of the electromechanicalvalve actuator. The antennas can have a variety of configurations aswell as be disposed at various locations in the system. For example, inone exemplary embodiment, both the system controller and antennaassociated therewith can be disposed on the implantable shunt system. Inanother embodiment, the controller can be contained within theimplantable shunt system but the antenna can be disposed on a separateimplant. In yet another exemplary embodiment, both the system controllerand antenna associated therewith can be disposed on an implant that isseparate from the shunt system.

Methods of regulating cerebrospinal fluid flow are also provided. Ingeneral, the method can include comparing a target value to a valuedetected by a sensor associated with an implantable shunt system, andactivating an electromechanical valve actuator of the implantable shuntsystem to adjust a resistance of a valve of the shunt system if thedetected value is not equal to the target value. The method can alsoinclude inputting one or more target values to an external programmingdevice and transmitting those values to a system controller of theimplantable shunt system. In one exemplary embodiment, any of the abovesteps can be repeated until the detected value is equal to the targetvalue.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more fully understood from the following detaileddescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a diagrammatic view of a system of the invention;

FIG. 1A is a cross-sectional perspective view of one embodiment of anapparatus for regulating fluid flow;

FIG. 2 is a schematic view of one embodiment of an electromechanicalvalve actuator;

FIG. 3 is a schematic view of another embodiment of an electromechanicalvalve actuator;

FIG. 4 is a schematic view of one embodiment of a shunt valve assemblyfor regulating fluid flow;

FIG. 5 is a schematic view of another embodiment of a shunt valveassembly for regulating fluid flow; and

FIG. 6 is a schematic view of another embodiment of a shunt valveassembly for regulating fluid flow.

DETAILED DESCRIPTION OF THE INVENTION

Certain exemplary embodiments will now be described to provide anoverall understanding of the principles of the structure, function,manufacture, and use of the devices and methods disclosed herein. One ormore examples of these embodiments are illustrated in the accompanyingdrawings. Those skilled in the art will understand that the devices andmethods specifically described herein and illustrated in theaccompanying drawings are non-limiting exemplary embodiments and thatthe scope of the present invention is defined solely by the claims. Thefeatures illustrated or described in connection with one exemplaryembodiment may be combined with the features of other embodiments. Suchmodifications and variations are intended to be included within thescope of the present invention.

Methods and devices for regulating and directing bodily fluids from oneregion of a patient to another region are disclosed. In general, anapparatus 10 (illustrated in FIG. 1) is provided that can include animplantable shunt system 12 and a system controller 18. While a varietyof configurations are available, in one exemplary embodiment, theapparatus 10 can have an adjustable valve 14 for regulating the flow offluid, a sensor element 20 for measuring a physiological characteristicof a patient, and an electromechanical valve actuator 16 that can beadapted to adjust a resistance of the valve. As used herein,“electromechanical actuator” includes mechanical systems (or mechanisms)that are actuated or controlled electrically such as, but not limitedto, electric motors, solenoids, and linear actuators. The implantableshunt system can be in electrical communication with the systemcontroller 18 which may or may not be provided within the shunt systemhousing. The system controller 18 can generally be adapted to receive aphysiological characteristic of the patient from the sensor 20 andoperate the electromechanical valve actuator 16 to adjust a resistanceof the valve 14. The system controller 18 may also receive instructionsfrom an external programming device 22. The apparatus can be batterypowered (i.e., by a battery contained therein) or can be powered by anexternal component. Although the device is shown and described asregulating the flow of cerebrospinal fluid (CSF), one skilled in the artwill appreciate that the device can be used to regulate the flow of anybodily fluid.

FIG. 1A illustrates one exemplary embodiment of an apparatus 100 forregulating fluid flow. As indicated above, the apparatus can generallyinclude an implantable shunt system 102 and a system controller 104. Theshunt system 102 can be adapted to drain excess fluid from one area of apatient's body and direct the fluid to another site in the body. Avariety of configurations are available for the shunt system 102. Asused herein, a shunt refers to any device that diverts a flow of fluid.A person of ordinary skill in the art will recognize that a variety ofconfigurations for shunt devices are possible. In one exemplaryembodiment, shown in FIG. 1A, the shunt system 102 includes a housing106 defining an inlet port 110, an outlet port 112, and a chamber 108oriented between the inlet port 110 and the outlet port 112. The inletand outlet ports 110, 112 can be coupled to inlet and outlet or drainagecatheters 450, respectively (FIGS. 4-6). For example, in one embodiment,the apparatus can be used to treat hydrocephalus and the inlet catheteris inserted within a ventricle of a patient's brain and the drainagecatheter is inserted within another area of the patient's body, such asthe peritoneum. During operation, the shunt system 102 can carry CSF,originating from the ventricle, from the inlet catheter, through thechamber, and to the drainage catheter.

The implantable shunt system 102 can also include an adjustable valve114 for regulating the flow of fluid. The resistance of the valve 114can be adjusted within the housing 106 to set a pressure threshold atwhich excess CSF begins to flow from the ventricle of a brain throughthe valve 114 and to another area of a patient's body. While the valve114 can have several configurations, in an exemplary embodiment, shownin FIG. 1A, the valve 114 takes the form of a ball valve. As shown, theball 116 is disposed in the chamber 108 of the housing 106 and is seatedin a circular orifice 118. Although the valve 114 is shown and describedas a ball valve, one skilled in the art will appreciate that a number ofvalve configurations are available for use with the implantable shuntsystem 102. The ball 116 can act as a stop member and regulate the fluidflow through the shunt system 102. For example, fluid can be preventedfrom flowing through the shunt system when the ball 116 is fully seatedwithin the circular orifice 118. Alternatively, fluid can be allowed toflow through the shunt system 102 when the pressure in the ventricleexceeds the force being applied to the ball 116 to seat it in thecircular orifice 118. Thus, varying the force applied to the ball 116can be effective to vary the resistance of the valve 114 (i.e., thepressure threshold at which fluid begins to flow through the valve 114).

A variety of techniques can be used to adjust the resistance of thevalve 114. For example, in one exemplary embodiment, anelectromechanical valve actuator 120 can be operatively associated withthe valve 114 and adapted to adjust a resistance of the valve 114. Theelectromechanical valve actuator 120 can be configured to adjust andmaintain the pressure threshold at which fluid begins to flow throughthe valve 114 thereby reducing the risk of either over- orunder-drainage of CSF from a brain ventricle. The electromechanicalvalve actuator 120 can generally include a spring 122 and a pressuresetting mechanism 124. The electromechanical valve actuator 120 caneffectively prevent movement of the valve 114, such as when the shuntsystem is exposed to environmental magnetic forces. In certain cases,for example, the shunt system 102 can be subjected to a strong externalmagnetic field, such as when a patient having an implanted shunt system102 undergoes an magnetic resonance imaging (MRI) procedure. Themagnetic field generates a force on the shunt system 102 that can inducemotion of the pressure setting mechanism 124 and can cause the pressuresetting mechanism 124 to adjust the position of the valve 114. Theelectromechanical valve actuator 120, however, can lock the valve 114 inplace to maintain a set pressure threshold within the shunt system 102when exposed to the magnetic field. FIGS. 1-3 illustrate a variety ofexemplary embodiments of electromechanical valve actuators 120 for usewith the shunt system 102 described herein. One skilled in the art willappreciate that various springs and configurations of pressure settingmechanisms can form the electromechanical valve actuator, and theactuator should not be limited to the features and configurationsdescribed below.

As shown, the electromechanical valve actuator 120 includes a leafspring 122 that is coupled to a pressure setting mechanism 124 having acantilever 126 and a rotor assembly 128. As indicated above, the ball116 of the ball valve can regulate the fluid flow through the shuntsystem. The ball 116 can be operatively joined to a first end 122 a ofthe cantilevered spring 122 which a second end 122 b of the spring 122can engage a stair array 130 of the rotor assembly 128. In thisembodiment, the rotor assembly 128 can include the stair-step array 130in the form of a spiral staircase to provide pressure settings indiscrete steps. The rotor assembly 128 can also include an actuationmechanism 132 that is configured to rotate the stair array 130 withrespect to the cantilevered spring 122. In general, the mechanism 132can include a motor 134 that is operatively associated with the stairarray 130. For example, in one exemplary embodiment, shown in FIG. 1A,the mechanism 132 includes a micro-motor 134 that is coupled to thestair array 130 via gear teeth provided on each (not shown). A varietyof motors can be used to rotate the stair array 130 including, but notlimited to, micro-motors, stepper-motors, and piezo-motors.

In use, the actuation mechanism 132 of electromechanical valve actuator120 can rotate the spiral stair array 130 with respect to thecantilevered spring 122, and the second end 122 b of the spring 122 canmove up or down each stair of the array 130. Moving the second end 122 bof the spring 122 up or down can be effective to change the angle ofdeflection of the spring 122 (e.g., relative to the cantilever 126). Thechange in the angle of deflection of the spring 122, in turn, alters theforce that is exerted by the spring 122 on the ball 116. As indicatedabove, changing the force applied to the ball 116 can result in acorresponding increase or decrease of the established pressure thresholdat which fluid begins to flow through the shunt system 102.

An antenna 430 can also be provided to allow for non-invasive control ofthe electromechanical valve actuator 120. As is described below indetail, one or more antennas 430 can have a variety of configurations aswell as be disposed at various locations throughout the system.Referring generally to FIG. 1, the shunt system 12, system controller18, and programming device 22 can include signal transmitters/receiversor antennas 430 that can be configured to send and/or receive signalsfrom one another to allow the individual components of the apparatus 10to communicate with each other as well as facilitate non-invasivecontrol of the apparatus 10.

FIG. 2 illustrates another exemplary embodiment of an electromechanicalvalve actuator 200 for use with the implantable shunt system 102. Asshown, the electromechanical valve actuator 200 includes a leaf spring202 that is operatively associated with a pressure setting mechanism 204that takes the form of a gear assembly 206. Similar to the embodimentshown in FIG. 1A, a first end 202 a of the leaf spring 202 can beoperatively associated with the ball 116 of the ball valve and a secondend 202 b of the spring 202 can engage the gear assembly 206. The gearassembly 206 can include first and second gears 206 a, 206 b. The firstgear 206 a can have a series of helical steps (not shown) formed thereonand can be adapted to engage the spring 202. The second gear 206 b canengage the first gear 206 a as well as be operatively associated with anactuation mechanism 208 of the gear assembly 206. The actuationmechanism 208 can be configured to drive the gears 206 a, 206 b androtate the helical steps with respect to the spring 202. The mechanism208 shown in FIG. 2 includes a micro-motor 210 that is coupled to thesecond gear 206 b via a cylindrical motor shaft 212. As indicated above,a variety of motors can be used to rotate the stair array including, butnot limited to, micro-motors, stepper-motors, and piezo-motors. In use,the actuation mechanism 208 can drive the gear assembly 206 to rotatethe helical steps with respect to the spring 202 and move the second end202 b of the spring 202 up or down the steps. As described above, suchmovement can be effective to change in the angle of deflection of thespring 202 thereby altering the force that is exerted on the ball 116and increasing or decreasing the established pressure threshold at whichfluid begins to flow through the shunt system.

Another exemplary embodiment of an electromechanical valve actuator 300is shown in FIG. 3. As shown, the electromechanical valve actuator 300includes a helical spring 302 that is coupled to a pressure settingmechanism 304 having a stop member 306 and motor assembly 308. A firstend 302 a of the helical spring 302 can engage the ball 116 of the ballvalve, and a second end 302 b of the spring 302 can abut a distal facingsurface 307 of the stop member 306. The stop member 306 can havevirtually any configuration, for example, as shown in FIG. 3, the stopmember 306 is a generally cylindrical cap that has a closed distal end306 b and an open proximal end 306 a with a bore 309 formed therein. Thebore 309 can be threaded and adapted to receive and engage a threadedshaft 308 a of the motor assembly 308. A motor 308 b, such as onedescribed above, can drive the threaded shaft 308 a to move the stopmember 306 in the proximal and/or distal directions. The closed distalend 306 b of the stop member 306 can be configured to apply a force tothe spring 302 such that distal movement of the stop member 306 iseffective to compress the spring 302 and alter the force that is exertedby the spring 302 on the ball 116. As indicated above, changing theforce applied to the ball 116 can result in a corresponding increase ordecrease of the established pressure threshold at which fluid begins toflow through the shunt system.

The implantable shunt system can further include a sensor element formeasuring a physiological characteristic of a patient. The sensorelement can be coupled to the valve or it can be separate from thevalve. For example, as shown in FIGS. 4-6, the sensor element 402 is inelectrical communication with the shunt system 401 and is coupled to thesystem via wires 402 a. Additionally, while the sensor element 402 isshown as being positioned within the CSF flow pathway 406 of the shuntsystem 401, in another exemplary embodiment, the sensor element 402 canbe located outside of the CSF flow pathway 406 though still residingwithin the ventricular cavity of the patient. The sensor element 402 canbe configured to measure a variety of physiological characteristics of apatient including, but not limited to, CSF pressure. Although the shuntsystem 401 is shown as having a single sensor element 402, one skilledin the art will appreciate that the system can include multiple sensorelements having several different configurations. For example, in oneembodiment, the system 401 can include multiple pressure sensors tomeasure the CSF pressure at various points in the ventricular cavity. Inanother exemplary embodiment, the system 401 can include multiple sensorelements each configured to measure a different physiologicalcharacteristic of a patient.

As indicated above, the apparatus 400 for regulating fluid flow can alsoinclude a system controller 408. In general, the controller 408 can bein electrical communication with the implantable shunt system 401 andcan be adapted to receive the physiological characteristic measured bythe sensor element 402 and to operate the electromechanical valveactuator 410 to adjust a resistance of the valve 114. For example, thesystem controller 408 can be configured to receive an input signal thatis generated by the sensor element 402 and is representative of themeasured value of the physiological characteristic (e.g., the CSFpressure). The system controller 408 can also be configured to generateand transmit to the electromechanical valve actuator 410 an outputcontrol signal that commands the actuator 410 to adjust the resistanceof the valve 114. A variety of configurations are available for thesystem controller 408. For example, as shown in FIGS. 4 and 5, in oneexemplary embodiment, the controller 408 is contained within theimplantable shunt system 401. Depending on the size and configuration ofthe electromechanical valve actuator 410, it may not be desirable tohave the controller 408 contained within the shunt system 401.Accordingly, in another exemplary embodiment, the controller 408 can bedisposed on an implant 412 that is separate from the implantable shuntsystem 401 (FIG. 6).

The system controller 408 can also include a processing unit such as,for example, a microprocessor, which enables the controller 408 tocompare the measured physiological characteristic (e.g., the measuredCSF pressure) detected by the sensor element 402 to a predeterminedtarget value for the physiological characteristic. The predeterminedtarget value can be ascertained through clinical assessment of thepatent and is therefore customized for each particular patient. Thistarget value can then be preset or programmed into the system controller408. In use, the system controller 408 can operate according to analgorithm which determines whether the value measured by the sensorelement 402 is higher than, lower than, or within an acceptable range ofthe target value. Based on this assessment, the algorithm can thendetermine whether the resistance of the valve 114 should be increased,decreased, or maintained in order to achieve the target CSF pressure forthe patient. For example, where the physiological characteristic beingmeasured is CSF pressure, the valve's resistance can be decreased if themeasured pressure is higher than the target pressure. Conversely, theresistance of the valve 114 can be increased if the measured pressure islower than the target pressure. The microprocessor can then generate anoutput control signal to the electromechanical valve actuator 410 whichcommands the actuator 410 to adjust its current resistance to thedesired resistance. If the measured value is essentially the same as, orwithin an acceptable range of the target value, then the currentresistance is maintained and no changes are made.

The apparatus 400 for regulating fluid flow can further include anexternal programming device 420 that is in communication with the systemcontroller 408. In general, the programming device 420 can include auser input element that allows an operator to input one or moreinstructions to be communicated to the system controller 408. Forexample, the external programming device 420 can be adapted to transmita signal to the system controller 408 that is representative of apredetermined target value for the CSF pressure of a patient. Theexternal programming device 420 can have a variety configurations and inone exemplary embodiment can take the form of a hand-held remotecontrol. The programming device 420 can include a display forcommunicating input and/or output values (e.g., the predetermined targetvalue for a physiological characteristic being measured and/or themeasured value of a physiological characteristic) to a user. In additionto communicating instructions to the system controller 408, theprogramming device 420 can also be adapted to power the implantableshunt system 401.

As indicated above, one or more antennas 430 can be provided to allowthe individual components of the apparatus 400 to communicate with eachother as well as facilitate non-invasive control of the apparatus 400.The implantable shunt system 401, system controller 408, and externalprogramming device 420 can be equipped with electronic circuitry similarto those for medical telemetry systems that communicate physiologicaldata (e.g., temperature, pressure, etc.) between an implant and areceiver unit. For example, the system controller 408 can be configuredto generate an analog data signal that is then converted electronicallyto a digital pulse which is then transmitted by radiofrequency (RF) tothe external programming device 420. As illustrated in FIGS. 4-6, theshunt system 401, system controller 408, and programming device 420include signal transmitters/receivers or antennas 430 that can beconfigured to send and/or receive signals from one another. Suchcommunication can provide non-invasive control of the electromechanicalvalve actuator 410. The antennas 430 can have a variety ofconfigurations as well as be disposed at various locations in thesystem. For example, in one exemplary embodiment shown in FIG. 4, boththe system controller 408 and antenna 430 associated therewith aredisposed on the implantable shunt system 401. In another embodiment,shown in FIG. 5, the controller 408 is contained within the implantableshunt system 401 but the antenna 430 is disposed on a separate implant430 a. Such a configuration can allow for a larger, more powerfulantenna to be placed in a more convenient location (e.g., a patient'sarm rather than their head). In yet another exemplary embodiment,illustrated in FIG. 6, both the system controller 408 and antenna 430associated therewith are disposed on an implant 412 separate from theimplantable shunt system 401. Similar to the embodiment shown in FIG. 5,this embodiment can provide less restriction on the size of the systemcontroller 408 and antenna 430, as these components are not part of theshunt system 401. One skilled in the art will recognize that these aremerely examples of the forms of remote communication suitable for usewith the fluid regulating apparatus 400 disclosed herein and a varietyof other forms of non-invasive communication can be utilized withoutdeparting from the scope of the present invention.

Methods of regulating cerebrospinal fluid flow are also provided. Ingeneral, the method can include comparing a target value to a valuedetected by a sensor 402 associated with an implantable shunt system401, and activating an electromechanical valve actuator 410 of theimplantable shunt system 401 to adjust a resistance of a valve 114 ofthe shunt system 401 if the detected value is not equal to the targetvalue.

In one exemplary embodiment, the method can include energizing theapparatus 400 with the external programming device 420 and detecting aphysiological characteristic of a ventricular cavity (e.g., CSFpressure). The measured value can then be compared to a predeterminedtarget value for that physiological characteristic. The predeterminedtarget value can be preset in the system controller 408 or can beprogrammed in the controller via the external programming device 420. Ifthe system controller 408 determines that the measured value is notequal to the target value, the controller 408 than determines whetherthe resistance for the valve 114 should be increased or deceasedaccordingly to achieve the predetermined target value for thatphysiological characteristic. The system controller 408 can thengenerate and transmit an activation signal to activate theelectromechanical valve actuator 410 and adjust a resistance of thevalve 114. If the measured value is essentially the same as, or withinan acceptable range of the target value, then no change is made to theresistance of the valve 114.

During the operation of the external programming device 420 (i.e., whenthe device 420 is applied to the patient and the apparatus 401 isenergized), data can be communicated between the device 420 and thesystem controller 408. For example, a user can input a target value tothe programming device 420 and the device can communicate datarepresentative of the target value to the system controller 408. Datacan also be communicated between the implantable shunt system 401 andthe system controller 408. The sensor element 402 can communicate datarepresentative of the measured value of a physiological characteristicto the system controller 408, and the controller 408 can communicate acommand to the electromechanical valve actuator 410 to adjust aresistance of the valve 114. More specifically, the system controller408 can detect a value of a physiological characteristic measured by thesensor element 402 by receiving an input signal generated from thesensor element 402 that contains data about the measured value of thephysiological characteristic. Similarly, the system controller 408 canadjust a resistance of the valve 114 by generating and transmitting anoutput control signal to the electromechanical valve actuator 410 thatcommands the actuator 410 to adjust a resistance of the valve 114.

In an application of the methods described above, if a patientexperiences discomfort and/or pain, the apparatus 401 can be energizedand data can be communicated from the external programming device 420 tothe system controller 408. The apparatus 401 can be energized by eitherthe patient himself or his attending physician. If the measured value isthe same as, or falls within an acceptable range of the target value,then the system controller 408 is programmed to make no changes to theresistance. If, however, the system controller 408 detects that themeasured value is higher or lower than the preset target value, thecontroller 408 sends a command to the electromechanical valve actuator410 to adjust a resistance of the valve 114. Then, after some time haselapsed (e.g., a day, two days, a week, etc.) to allow the patient'sphysiology to respond to the valve's 114 new resistance setting, and thepatient still experiences discomfort or pain, or simply wants todetermine the current value of a particular physiologicalcharacteristic, the apparatus 401 can again be energized to measure thecurrent value. If the system controller 408 does not detect a change inthe measured value from the previous reading, the controller 408 cansend another command to the electromechanical valve actuator 410 toadjust the resistance accordingly.

It is contemplated that the above steps can be repeated until anappropriate resistance is attained and the system controller 408 detectsthat the measured value is approaching or has approached the targetvalue for that patient. For example, the above steps can be repeatedwhenever the patient begins to experience pain or discomfort. However,to safeguard against repeated or excessive valve 114 adjustments withina short window of time, which could produce deleterious healthconsequences for the patient, the system controller 408 can include atimed shutoff mechanism which would limit the user's ability to adjustthe valve in a given time period. For example, the system controller's408 valve adjustment features can be configured to deactivate after eachuse until a preset amount of time (e.g., a day, two days, a week, etc.)has passed whereby the valve adjustment feature is automaticallyreactivated. Such a safeguard ensures that a sufficient amount of timepasses between adjustments so that the patient's physiology does notincur rapid CSF flow changes in a short amount of time. Of course, it iscontemplated that the system controller 408 can still be capable ofdetecting a physiological characteristic of the patient's ventricularcavity even when the device's valve adjustment features are not active.Hence, the patient can continue to monitor a physiologicalcharacteristic of his ventricular cavity using the apparatus 401 evenbetween stages of adjusting the valve 114.

One skilled in the art will appreciate further features and advantagesof the invention based on the above-described embodiments. Accordingly,the invention is not to be limited by what has been particularly shownand described, except as indicated by the appended claims. Allpublications and references cited herein are expressly incorporatedherein by reference in their entirety.

What is claimed is:
 1. An apparatus for regulating fluid flow,comprising: an implantable shunt system having: an adjustable valve forregulating the flow of fluid, a sensor element for measuring aphysiological characteristic of a patient, and an electromechanicalvalve actuator adapted to adjust a resistance of the valve; and a systemcontroller in electrical communication with the implantable shunt systemand adapted to receive the physiological characteristic of the patientand operate the electromechanical valve actuator to adjust a resistanceof the valve and thereby adjust a pressure threshold at which fluidbegins to flow through the valve; further comprising an externalprogramming device in communication with the system controller; whereinthe external programming device includes a display for communicating thephysiological characteristics of the patient to a user; and wherein theexternal programming device includes a user input element, the externalprogramming device being configured to communicate one or moreinstructions to the system controller based on user input.
 2. Theapparatus of claim 1, wherein the valve is a ball valve.
 3. Theapparatus of claim 1, wherein the electromechanical valve actuatorcomprises a spring operatively associated with a pressure settingmechanism, and at least one selected from the group consisting of anelectric motor, a solenoid, and a linear actuator mechanically coupledto the pressure setting mechanism to vary a pressure applied by thespring to thereby adjust the resistance of the valve.
 4. The apparatusof claim 3, wherein the spring is a leaf spring.
 5. The apparatus ofclaim 3, wherein the spring is a helical spring.
 6. The apparatus ofclaim 3, wherein the pressure setting mechanism includes a motor drivenrotor assembly adapted to adjust a resistance of the valve uponactuation of the motor.
 7. The apparatus of claim 3, wherein thepressure setting mechanism includes a motor driven stop member, the stopmember being adapted to apply a force to the spring to adjust aresistance of the valve.
 8. The apparatus of claim 1, wherein the sensorelement is a pressure sensor for detecting a cerebro-spinal fluidpressure.
 9. The apparatus of claim 8, wherein the system controllerincludes a microprocessor for comparing the measured pressure detectedby the sensor to a target pressure.
 10. The apparatus of claim 9,wherein the system controller is configured to receive an input signalgenerated from the external programming device, the signal beingrepresentative of the target pressure.
 11. The apparatus of claim 9,wherein the microprocessor is programmed to calculate a desiredresistance for the valve to achieve the target pressure.
 12. Theapparatus of claim 1, wherein the controller is contained within theimplantable shunt system.
 13. The apparatus of claim 1, furthercomprising an antenna in electrical communication with the systemcontroller for communicating with the external programming device. 14.The apparatus of claim 13, wherein the antenna is configured tocommunicate with the external programming device via RF communication.15. The apparatus of claim 13, wherein controller and antenna aredisposed on an implant separate from the implantable shunt system. 16.The apparatus of claim 1, wherein the implantable shunt system furtherincludes a second sensor element for measuring an additionalphysiological characteristic, the second sensor element being configuredto transmit data representing the measured value of the additionalphysiological characteristic to the system controller.
 17. The apparatusof claim 1, wherein the implantable shunt system further includes abattery for powering the system.
 18. The apparatus of claim 1, whereinthe external programming device is adapted to power the implantableshunt system.
 19. A system for regulating fluid flow, comprising: ahousing having an inlet port and an outlet port, the housing configuredto carry a fluid between the inlet port and the outlet port; a valvecoupled to the housing and in fluid communication with the inlet portand the outlet port, the valve having an electromechanical valveactuator mechanically coupled to the valve and adapted to adjust aresistance of the valve and thereby adjust a pressure threshold at whichfluid begins to flow through the valve; an internal system controller inelectrical communication with and adapted to operate theelectromechanical valve actuator; a sensor element in communication withthe system controller and adapted to measure a physiologicalcharacteristic of a patient; wherein the sensor element is a pressuresensor for detecting pressure variations within the ventricular cavity;and an external system controller adapted to communicate with theinternal system controller and modify the operating parameters thereof.20. The system of claim 19, wherein the valve is a ball valve.
 21. Thesystem of claim 20, wherein the electromechanical valve actuatorcomprises a spring operatively associated with a pressure settingmechanism, and at least one selected from the group consisting of anelectric motor, a solenoid, and a linear actuator mechanically coupledto the pressure setting mechanism to vary a pressure applied by thespring to thereby adjust the resistance of the valve.
 22. The system ofclaim 21, wherein the spring is a leaf spring.
 23. The system of claim21, wherein the spring is a helical spring.
 24. The system of claim 19,further comprising an antenna in electrical communication with theinternal system controller for communicating with the external systemcontroller.
 25. A method for regulating cerebrospinal fluid flow in ahydrocephalus patient, comprising: comparing a target value to a valuedetected by a sensor associated with an implantable shunt system;wherein the detected value is a physiological characteristic of theventricular cavity; and activating an electromechanical valve actuatorof the implantable shunt system to adjust a resistance of a valve of theshunt system if the detected value is not equal to the target value. 26.The method of claim 25, wherein detecting a value of a physiologicalcharacteristic comprises communicating data representative of thedetected value of the physiological characteristic from the sensorelement to a controller of the implantable shunt system.
 27. The methodof claim 26, further comprising generating an activation signal via thecontroller to activate the electromechanical valve actuator.
 28. Themethod of claim 27, wherein generating an activation signal to activatethe electromechanical valve actuator and adjust the resistance of thevalve comprises determining a desired resistance to achieve the targetvalue.
 29. The method of claim 25, further comprising transmitting thetarget value to a controller of the implantable shunt system.
 30. Themethod of claim 29, wherein the target value is transmitted via anexternal programming device.
 31. The method of claim 30, furthercomprising inputting one or more target values to the externalprogramming device.
 32. The method of claim 30, further comprisingenergizing the implantable shunt system with the external programmingdevice.
 33. The method of claim 25, wherein activating theelectromechanical valve actuator to adjust a resistance of the valve isrepeated until the detected value is equal to the target value.